Analytical Advances in the Quantitative and Qualitative Determination of Clonidine and Methyldopa: A Review

A gold electrode was used for the qualitative and quantitative electrochemical determination of analytical methomyl in a neutral electrolyte (0.050 M NaHCO3) using cyclic linear sweep voltammetry. In the potential range from -800 mV vs. SCE to 1000 mV vs. SCE the analytical methomyl was quantitatively determined in the concentration range 4.0-16 mg L-1. In the potential range from -1300 mV vs. SCE to 1300 mV vs. SCE, methomyl was qualitatively determined by two anodic and four cathodic reactions. Cycling the potential in this range for 150 min caused the degradation of the molecule, which was confirmed by HPLC analysis. On the other hand, technical methomyl exhibited an inhibition of the gold electrode surface due to the impurities.

The only stable isomer of the higher fullerene C76 of D2 symmetry was isolated from carbon soot by the new and advanced extraction and chromatographic methods and processes. Characterization of the isolated C76-D2 was performed by the IR(KBr) and UV/VIS method in the absorption mode. All of the experimentally observed infrared and electronic absorption bands are in excellent agreement with the theoretical calculations for this fullerene. The molar absorptivity ε and the integrated molar absorptivity Ψ of the observed entire new series of various characteristic, both deconvoluted and convoluted IR absorption bands of the C76-D2 isomer, in different integration ranges were determined. In addition, the molar extinction coefficients of its UV/VIS absorption bands were determined. The obtained novel IR and UV/VIS spectroscopic parameters are significant for the quantitative assessment of C76-D2. All the presented data are important both for its qualitative and quantitative determination, either in natural resources on Earth and in space or in artificially synthesized materials, electronic and optical devices, optical limiters, sensors, polymers, solar cells, nanophotonic lenses, diagnostic and therapeutic agents, pharmaceutical substances, for targeted drug delivery, incorporation of metal atoms, in biomedical engineering, industry, applied optical science, batteries, catalysts and so forth.

The qualitative determination by paper chromatography and the quantitative determination by high performance liquid chromatography (HPLC) of the Coenzyme Q system have been investigated for in 23 species of the genus Pichia. We have adapted HPLC to the quantitative analysis of the Coenzyme Q system. We have found the presence of 2,3 or 4 ubiquinones in the same Coenzyme Q extract.

Quantitative extraction studies from urine were carried out by addition of cocaine, benzoylecgonine, ecgonine methyl ester and ecgonine to urine samples. After hydrolysis to ecgonine the compounds were analyzed together. Ecgonine was isolated by a cation-exchange resin and purified by an anion-exchange resin. The quantitative determination was performed by GC after silylation with MSTFA. The recovery was 77% at a concentration of 150 μg ecgonine/ml urine. A qualitative determination of ecgonine by GC/MS was possible up to the detection limit of 20 ng/ ml. The method can be applied for the detection of cocaine abuse.

Quantitative and qualitative determination of six xanthones in Garcinia mangostana L. by LC–PDA and LC–ESI-MS

A methodology for the prediction of excitation energies for substituted chromophores on the basis of ground state structures has been developed. The formalism introduces the concept of "structural substituent excitation energy effect" for the rational prediction and quantification of the substituent effect in the excitation energy of a chromophore to an excited electronic state. This effect quantifies exclusively the excitation energy variation due to the structural changes of the chromophore induced by the substituent. Therefore, excitation bathochromic and hypsochromic shifts of substituted chromophores can be predicted on the basis of known ground and excited potential energy surfaces of a reference unsubstituted chromophore, together with the ground state minimum energy structure of the substituted chromophore. This formalism can be applied if the chemical substitution does not affect the nature of the electronic excitation, where the substituent effect can be understood as a force acting on the chromophore and provoking a structural change on it. The developed formalism provides a useful tool for quantitative and qualitative determination of the excitation energy of substituted chromophores and also for the analysis and determination of the structural changes affecting this energy. The proposed methodology has been applied to the prediction of the excitation energy to the first bright state of several S-nitrosothiols using the potential energy surfaces of methyl-S-nitrosothiol as a reference unsubstituted chromophore.

Eight commonly used sulfonylureas (SUs: nicosulfuron, thifensulfuron methyl, metsulfuron methyl, sulfometuron methyl, chlorsulfuron, bensulfuron methyl, tribenuron methyl, and chlorimuron methyl) and deuterium-labeled nicosulfuron (nicosulfuron-d(6)), used as an internal standard, were isolated from soil by solvent extraction and identified under quantitative and qualitative ion spray LC/MS/MS conditions using the selected reaction monitoring (SRM) mode of acquisition. The lower level of quantitation for these SUs in soil was determined at the 0.05 ppb level using a TurboIonSpray adapted LC/MS interface without a precolumn split and optimizing MS/MS tuning conditions for individual SUs. The eight SUs were qualitatively identified and quantitatively determined in soil. The standard curve for each SU was linear from 0.05 to 10 ppb. This SRM LC/MS method demonstrates high sensitivity and high specificity for these SUs in soil and shows at least a 400-fold improvement in sensitivity over previous reports. Acceptance criteria for forensically valid data are suggested for qualitative SRM LC/MS experiments. These include HPLC retention time reproducibility (±2%), at least two and preferably three precursor-product ions selected, and relative abundance criteria for selected ions (±20% absolute).

A simple, rapid, and environmentally safe liquid chromatographic (LC) method was developed for the qualitative and quantitative determination of pharmaceutical preparations of nalidixic acid. The new method was applied to commercial preparations of tablets and a suspension of nalidixic acid and found to be satisfactory for both quantitative and qualitative determinations. Previous LC methods either used chloroform to extract, which we were trying to eliminate, or used a mobile phase of about pH 2.5, which will destroy the column coating. The LC system for the new method uses sulfanilic acid as internal standard, a mu-Bondapak C18 column, and a mobile phase of methanol, 0.0045M dibasic potassium phosphate, and 0.0072M hexadecyltrimethylammonium bromide. The detection wavelength is 254 nm. The sample is dissolved in methanol, and an aliquot is injected through a 20 microL injection loop. Average recoveries ranged from 99.4 to 101.3%.

A screening method has been developed for the qualitative and quantitative determination of vanillin, ethylvanillin, coumarin and dihydrocoumarin. The compounds are qualitatively determined by thin-layer chromatography after extraction of tobacco and purification of the extract. The quantitative determination is made by gas chromatography: Coumarin and dihydrocoumarin are determined directly and vanillin and ethylvanillin after silylation in the form of trimethylsilyl derivatives. Detection limit: thin-layer chromatography = 1 µg, gas chromatography = 0.02 µg. The coefficient of variation of the results obtained amounts to 2.4 % for vanillin and to 6.7 % for coumarin

Boswellia serrata and Boswellia sacra (syn. B. carteri) are important medicinal plants widely used for their content of bioactive lipophilic triterpenes. The qualitative and quantitative determination of boswellic acids (BAs) is important for their use in dietary supplements aimed to provide a support for osteoarthritic and inflammatory diseases. We used High Performance Liquid Chromatography (HPLC)-Diode Array Detector (DAD) coupled to ElectroSpray Ionization and tandem Mass Spectrometry (ESI-MS/MS) for the qualitative and quantitative determination of BAs extracted from the gum resins of B. sacra and B. serrata. Limit of detection (LOD), limit of quantification (LOQ), and Matrix Effect were assessed in order to validate quantitative data. Here we show that the BAs quantitative determination was 491.20 g·kg−1 d. wt (49%) in B. sacra and 295.25 g·kg−1 d. wt (30%) in B. serrata. Lower percentages of BAs content were obtained when BAs were expressed on the gum resin weight (29% and 16% for B. sacra and B. serrata, respectively). The content of Acetyl-11-Keto-β-Boswellic Acid (AKBA) was higher in B. sacra (70.81 g·kg−1 d. wt; 7%) than in B. serrata (7.35 g·kg−1 d. wt; 0.7%). Our results show that any claim of BAs content in either B. sacra or B. serrata gum resins equal to or higher than 70% or AKBA contents of 30% are simply unrealistic or based on a wrong quantitative determination.

Ten male rhesus monkeys, each weighing 3.5 kg, were divided into four groups of 3, 3, 2, and 2, and were fed daily with 100 g pelleted food containing 300, 30, 3, and 0 ppm cadmium, respectively. Urine samples were collected every 2 weeks and blood samples every 4 weeks. One monkey each of the 300 and 30 ppm groups was autopsied for pathological examination and tissue cadmium determination at the week 24 of the experiment; the remaining 8 animals were killed after 55 weeks.The lowest exposed group (3 ppm) did not show any specific biological response to cadmium over a period of 55 weeks. In the 30 ppm group, no significant changes were observed for up to 24 weeks, although cadmium concentration in the renal cortex and urine at 24 weeks were 300 μg/g wet weight and 18 μg/l., respectively. Plasma urea nitrogen and urine protein (quantitative determination) increased after 30 and 36 weeks. At 55 weeks of the experiment, qualitative tests were negative for low molecular weight proteinuria and glycosuria, and the results remained normal for renal and liver function tests and blood analysis, although cadmium concentrations in the renal cortex of two monkeys were 460 and 730 μg/g wet weight and those in the liver were 110 and 160 μg/g wet weight, respectively.In the highest exposure group (300 ppm), urine cadmium increased to 250 μg/l. by 11 weeks, and urine retinol-binding protein, plasma GOT, GPT, and LDH increased after 12 weeks. Proteinuria (quantitative determination), glycosuria, aminoaciduria (panaminoaciduria), and erythrocytopenia were observed after 16 weeks, when urine cadmium was 500–900 μg/l. Hypohemoglobinopathy and proteinuria (qualitative determination) were observed after 20 and 24 weeks, while cadmium concentrations in the renal cortex and the liver were 760 and 430 μg/g wet weight at 24 weeks, respectively. Slightly depressed tubular reabsorption of phosphate, increased urine β2-microglobulin, increased plasma urea nitrogen, and increased plasma α2-globulin fraction (electrophoresis) were observed between 28 and 30 weeks of the experiment. Creatinine clearance and plasma cholinesterase decreased after 47 and 54 weeks, respectively. Cadmium concentrations in the renal cortex and the liver of two monkeys at 55 weeks were 350 and 580 μg/g wet weight and 410 and 630 μg/g wet weight, respectively. Pathological examinations revealed denaturation, destruction, and regeneration of the epithelial cells in renal proximal tubules, but no pathological changes in osseous tissues.Critical cadmium concentration in the renal cortex was estimated to be 380 μg/g wet weight for low molecular weight proteinuria and 470 μg/g wet weight for proteinuria, glycosuria, and aminoaciduria. Critical concentration in the liver was also estimated to be 210 μg/g wet weight. The apparent biological half-time of cadmium in monkeys at autopsied stage was calculated to be 0.66, 6.4, 5.2, and 22.4 years for the 300, 30, 3, and 0 ppm groups, respectively.ImagesFIGURE 16.

Ten male rhesus monkeys, each weighing 3.5 kg, were divided into four groups of 3, 3, 2, and 2, and were fed daily with 100 g pelleted food containing 300, 30, 3, and 0 ppm cadmium, respectively. Urine samples were collected every 2 weeks and blood samples every 4 weeks. One monkey each of the 300 and 30 ppm groups was autopsied for pathological examination and tissue cadmium determination at the week 24 of the experiment; the remaining 8 animals were killed after 55 weeks. The lowest exposed group (3 ppm) did not show any specific biological response to cadmium over a period of 55 weeks. In the 30 ppm group, no significant changes were observed for up to 24 weeks, although cadmium concentration in the renal cortex and urine at 24 weeks were 300 μg/g wet weight and 18 μg/l., respectively. Plasma urea nitrogen and urine protein (quantitative determination) increased after 30 and 36 weeks. At 55 weeks of the experiment, qualitative tests were negative for low molecular weight proteinuria and glycosuria, and the results remained normal for renal and liver function tests and blood analysis, although cadmium concentrations in the renal cortex of two monkeys were 460 and 730 μg/g wet weight and those in the liver were 110 and 160 μg/g wet weight, respectively. In the highest exposure group (300 ppm), urine cadmium increased to 250 μg/l. by 11 weeks, and urine retinol-binding protein, plasma GOT, GPT, and LDH increased after 12 weeks. Proteinuria (quantitative determination), glycosuria, aminoaciduria (panaminoaciduria), and erythrocytopenia were observed after 16 weeks, when urine cadmium was 500–900 μg/l. Hypohemoglobinopathy and proteinuria (qualitative determination) were observed after 20 and 24 weeks, while cadmium concentrations in the renal cortex and the liver were 760 and 430 μg/g wet weight at 24 weeks, respectively. Slightly depressed tubular reabsorption of phosphate, increased urine β2-microglobulin, increased plasma urea nitrogen, and increased plasma α2-globulin fraction (electrophoresis) were observed between 28 and 30 weeks of the experiment. Creatinine clearance and plasma cholinesterase decreased after 47 and 54 weeks, respectively. Cadmium concentrations in the renal cortex and the liver of two monkeys at 55 weeks were 350 and 580 μg/g wet weight and 410 and 630 μg/g wet weight, respectively. Pathological examinations revealed denaturation, destruction, and regeneration of the epithelial cells in renal proximal tubules, but no pathological changes in osseous tissues. Critical cadmium concentration in the renal cortex was estimated to be 380 μg/g wet weight for low molecular weight proteinuria and 470 μg/g wet weight for proteinuria, glycosuria, and aminoaciduria. Critical concentration in the liver was also estimated to be 210 μg/g wet weight. The apparent biological half-time of cadmium in monkeys at autopsied stage was calculated to be 0.66, 6.4, 5.2, and 22.4 years for the 300, 30, 3, and 0 ppm groups, respectively.

The determination of polycyclic aromatic hydrocarbons (PAHs) in coal tar was systematically studied by the high performance liquid chromatography (HPLC), in which involved separation, qualitative and quantitative determination of PAHs. The series of key techniques and experiences were summarized. To ensure finely separation of PAHs PAH, using C18 bonding silica gel column, mobile phase of methanol-water, and theoretical plate number of column more than 5600 were needed. For quantitative determination, the external standard (E-X) quantitative method and external standard - response factor (E-F) quantitative method were recommended. For accurately quantitative determine PAHs, the key technologies were recommended including choice of the optimum solvent of samples preparation and optimum concentration and using ultrasonic treatment, etc. In addition, some determination typical coal tars were also given and recommended. .

The determination of polycyclic aromatic hydrocarbons (PAHs) in coal tar was systematically studied by the high performance liquid chromatography (HPLC), in which involved separation, qualitative and quantitative determination of PAHs. The series of key techniques and experiences were summarized. To ensure finely separation of PAHs PAH, using C18 bonding silica gel column, mobile phase of methanol-water, and theoretical plate number of column more than 5600 were needed. For quantitative determination, the external standard (E-X) quantitative method and external standard - response factor (E-F) quantitative method were recommended. For accurately quantitative determine PAHs, the key technologies were recommended including choice of the optimum solvent of samples preparation and optimum concentration and using ultrasonic treatment, etc. In addition, some determination typical coal tars were also given and recommended. .

Zur spektrochemie der metalloide F, Cl, Br, J, S, Se